import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 98152
 * Date: 2024-11-14
 * Time: 15:45
 */
public class Test {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int x = in.nextInt();
        for(int i = 1; i < x/2; i++) {
            int y1 = i*i-x;
            int y2 = (i+1)*(i+1)-x;
            if(y1 < 0 && y2 > 0) {
                if(-y1 < y2) {
                    int y = i*i;
                    System.out.println(y);
                }else {
                    int y = (i+1)*(i+1);
                    System.out.println(y);
                }
                break;
            }
        }
    }
}
